This invention relates to a sprocket-wheel, especially for chain drives of mining machines and equipments such as push-plate conveyors and mining equipment.
In known designs of sprocket-wheels the active chain links settle down in seats between the working surfaces of the teeth. The number of these seats equals to that of the teeth of the sprocket-wheel. The construction of the teeth and seats is of such a type that the seat is formed in tooth spaces, and is from all sides limited by side retaining walls. In these seats the active chain links rest. These are sometimes called lying chain links.
The results of tests on the work of known sprocket wheels show that the profile of the teeth and seats of the sprocket-wheel cause considerable problems and difficulties in the operation of the sprocket-wheel. These problems and difficulties increase with progress of the wear of chains and sprocket-wheels, and thereby reduces the performance thereof. It results in short life of the chains and sprocket-wheels.
Known sprocket-wheels show substantial disadvantages. The effective co-operation of the sprocket-wheel with the chain occurs essentially only within small angular displacement of the sprocket-wheel, usually not exceeding the value of 2.pi./Z, wherein Z is the number of teeth of the sprocket wheel. Actually only two teeth are loaded and the seat of the sprocket-wheel, which is situated between the teeth. The remaining teeth remaining in contact with the chain links are relieved. The form coupling occuring on small wheel sector between the teeth of the sprocket-wheel and the chain links causes development of high unitary pressures between the rubbing surfaces, as well as relatively severe transmission of pressures from the tooth in mesh with the chain onto that tooth just coming into mesh next on the sprocket-wheel.
A very substantial disadvantage of known sprocket-wheels consists also in limited possibility of free displacement of the active chain links within the seats in the sense of rotation of the sprocket-wheel. The length of the seat situated between two teeth is limited thereby. An extension of the length may be achieved only through a reduction of the thickness of the tooth. This, however, also reduces the strength and life of the sprocket-wheel. The limited ability to free displacement within the seats in the sense of rotation of the sprocket-wheel is a cause of stepwise indenting of the active chain links down into the seats in the form of wear of the chain links and of the sprocket-wheel. That occurrence causes seizing of the chain links in the seats, an intensification of the wear of the tooth surface, and necessity to employ chain pushers in drives. Disadvantageous effects of indenting and seizing of the chain links in the seats reside in generating considerable, periodical and dynamic forces in the chain.
The object of the present invention is to provide a sprocket-wheel which is free from the aforementioned disadvantages. It is also an object to eliminate chain pushers from the drive.